The overall objective of this research proposal continues to be the characterization of myocardial properties and performance in man. The specific gaols set for the current year of investigation include further analysis of myocardial compliance and the determinants of left ventricular diastolic properties. As mentioned above, current goals in our laboratory include further investigation of the factors influencing ventricular compliance and contractility. In the next year we hope to: a) Examine the effects of chronic afterload and preload stresses and ventricular compliance. We plan to do this by studying left ventricular pressure-diameter relations in patients with chronic pressure overload (e.gl aortic stenosis) and comparing the results to findings in those with chronic volume overload (e.g. patients with mitral or aortic regurgitation. b) Continue studies on the effects of exercise stress (both isometric and dynamic) and myocardial performance. Studies completed in our laboratory during the past year have supported the hypothesis that isometric exertion is accompanied by an increase in left ventricular myocardial contractility. We would now like to examine the influence of dynamic exercise on inotropic state, particularly in subjects with left ventricular failure and presumably impaired inotropic reserve. c) Examine the ventricular stress-strain relationship by studying complete ventricular pressure-volume plots derived from a computerized analysis of left ventricular bi-plane cineangiography.